1. Field of the Invention
The present invention relates to semiconductor wet processing equipment and to a method of loading lots of semiconductor wafers onto and unloading the lots from the semiconductor wet processing equipment. More particularly, the present invention relates to semiconductor wet processing equipment capable of automatically unloading lots of semiconductor wafers in the event of an emergency.
2. Description of the Related Art
Generally speaking, fabricating semiconductor devices requires a highly precise execution of numerous manufacturing processes. Highly functional pieces of semiconductor fabrication equipment including, e.g., wet processing equipment, are arranged along a semiconductor fabrication line to perform these highly precise processes.
The elaborate operations of the equipment are monitored by an operator through a control system that is also provided on the semiconductor fabrication line. The operator uses the information provided by the control system to enhance the operation efficiency of the processing equipment.
FIG. 1 shows wet processing equipment 100 for performing a wet semiconductor manufacturing process. Lots 1 of semiconductor wafers, loaded in cassettes 3 traveling along the semiconductor fabrication line, are loaded onto the wet processing equipment 100 so that the wafers can be processed.
At this time, the operator monitors the operating state of the wet processing equipment 100 through an operator interface personal computer (O/I PC) 7 that is connected to the wet processing equipment 100. The wet processing equipment 100 is, in turn, connected to a host computer 6 by an equipment server 5. The host computer 6 is thus on-line with the O/I PC 7.
When the operator inputs basic fabrication data, e.g., the ID (identification) of a lot 1 to be processed and the ID of the wet processing equipment 100 for processing the wafers of lot 1, into the host computer 6 through the O/I PC 7, the host computer 6 searches its database for appropriate wet process condition data. Thereafter, the operator checks the wet process condition data and inputs a process commencing command or a process terminating command. Depending on the command, the lot 1 is rapidly tracked in or out of the wet processing equipment 100.
An input port unit 10 and an output port unit 20 are respectively provided at opposite ends of a body 30 of the wet processing equipment 100. The input port unit 10 and the output port unit 20 provide a loading position A and an unloading position B at which the lot 1 is loaded onto the wet processing equipment 100 and is unloaded therefrom, respectively. When a loading cassette 3 is loaded onto an input port table 11 by an auto-guided vehicle (AGV) under the control of an AGV server 8, a loading arm 13 received in a loading slit 12 formed in the input port unit 10 handles the cassette 3 and moves the cassette 3 to the loading position A. The wafers contained in the loading cassette 3 can be accurately introduced from this position into a wet process bath 31 by a robot arm 2, the wafers being processed rapidly in the wet process bath 31.
In addition, an unloading arm 23, received in an unloading slit 22 formed in an output port table 21 of the output port unit 20, handles an unloading cassette 4. Wafers are carried out from the wet process bath 31 and are placed in the unloading cassette 4. The unloading arm 23 places the unloading cassette 4 at an unloading position B on the output port desk 21, from which position the lot 1 can be rapidly unloaded from the wet processing equipment 100 by the AGV.
However, such conventional semiconductor wet processing equipment has several problems.
First, in the event of an emergency, such as an error in a process condition detected by the operator while the lot is waiting at the loading position of the input port unit, the lot should be rapidly unloaded from the processing equipment. At this time, however, the output port unit is disposed far away from the input port unit. As a result, it is impossible to rapidly unload the lot.
Therefore, the lot must be unloaded by hand. However, a large amount of manual labor and time is required to unload the lot waiting at the loading position of the input port unit.
Furthermore, a lot that is manually unloaded from the input port unit may collide with a lot that is being automatically loaded onto the processing equipment at the loading position. Operational problems may occur due to such a collision of the lots.